Printing inks

ABSTRACT

A lithographic printing ink contains a lithographic varnish containing an alkali soluble or dispersible binder material which is the reaction product of an acid functional hard resin with a fatty ester oil and/or an alkyd resin.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is concerned with improvements in and relating toprinting inks, especially printing inks for use in lithographic printingprocesses such as offset lithography.

2. Description of the Related Art

It is an essential requirement of inks for use in lithographic printingprocesses that they be oleophilic in character and, accordingly, inorder to wash them from printing apparatus it has been considerednecessary to use organic solvent systems as wash media. It has beenproposed, e.g. in WO94/06873, to provide lithographic inks which can bewashed from printing apparatus by the use of aqueous wash media, suchinks containing at least one component containing free carboxylic acidgroups so that the component can be rendered hydrophilic by complete orpartial neutralization of the carboxylic acid groups, i.e. by using analkaline aqueous wash medium. In the unneutralized form the component issufficiently hydrophobic to make it suitable for use in a lithographicprinting ink.

Typically, the carboxylic acid group-containing component used in thevarious lithographic inks particularly described in WO94/06873 is analkyd resin having an acid value of 25 mgKOH/g or more and, in order toobtain washability, using an aqueous alkaline wash, for the ink as awhole, relatively large amounts of such alkyd resins have to beemployed, with consequent restraints on flexibility of formulation oftenwith a reduction in the potential printing properties of the resultantink.

SUMMARY OF THE INVENTION

It has now been found, in accordance with the present invention, thatthe reaction products of relatively highly acid functional hard resinswith vegetable oils or like aliphatic carboxylic acid ester oils and/oralkyd resins can serve as useful components of lithographic printinginks, capable of affording the ink with the ability to be washed from aprinting press using an aqueous alkaline wash medium and also making itpossible to formulate a wide range of inks having good overall printingproperties.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following specification aliphatic carboxylic acid ester oils(including vegetable oils, marine oils and the like synthetic products)will simply be referred to as "fatty ester oils".

Accordingly, one embodiment of the present invention provides alithographic printing ink containing an alkali-soluble or dispersiblebinder material which is the reaction product of an acid functional hardresin with a fatty ester oil and/or an alkyd resin, wherein the hardresin has an acid value of at least 50 mgKOH/g. The invention alsoprovides a method of lithographic printing using such an ink.

As discussed in more detail below, printing inks in accordance with theinvention will also contain other components, such as diluents,colourants, other resinous binder materials, drying agents etc. However,an essential component of the printing inks of the invention is thereaction product of an acid functional hard resin with a fatty ester oiland/or an alkyd resin.

Hard resins are well-known components of printing inks such as offsetlithographic inks and are solid, fusible resins, typically having amelting point of 100° C. or higher (see, for example, "The Printing InkManual", Fifth Edition, R. H. Leach ed., Blueprint, 1993, at pages369/370).

Suitable hard resins for use in the production of the acidic reactionproduct include rosin esters, phenolic modified rosin esters, rosinmodified maleic resins, rosin modified fumaric resins, formophenolicresins, terpene phenolic resins, hydrocarbon resins, phenolic resins androsin and maleic modified hydrocarbon resins. Such resins are described,for example, in "Printing Inks for Lithography", Owen D. J., SITATechnology, 1994, at pages 58-72; "A Manual for Resins for SurfaceCoatings", Vol. I, (Second Edition), Goldring and Hayward, SITATechnology 1994, at pages 93-105 and 109-113. In contrast to the hardresins used in conventional lithgraphic inks, the hard resins used inaccordance with the invention must be highly acid functional and musthave an acid value of at least 50 mgKOH/g. Preferably though, this acidvalue is from 100 to 300 mgKOH/g, especially 150 to 250 mgKOH/g.Suitable commercially available highly acid functional hard resinsinclude K-1614 ex Lawter (acid value 190-205), Alsynol RC14 ex DSM (acidvalue 275-300), Filtrez 575 ex Akzo USA (acid value 210), Unirez 8100 exUnion Camp (acid value 105), Unirez 8200 ex Union Camp (acid value 190),Erkapol 209 ex Kraemer (acid value 172), Dertophenon 160 ex DRT (acidvalue 62) and Ennesin A100 ex Wolstenholme (acid value 109).

The other component from which the reaction product is derived comprisesa fatty ester oil and/or an alkyd resin. The oil, which is preferablyderived from one or more fatty acids containing at least 8 carbon atoms,e.g. C₈ -C₂₂ acids, may be a drying, semi-drying or non-drying oil orchemically modified derivative thereof such as linseed oil, tung oil,oiticia oil, perilla oil, dehydrated castor oil, soya bean oil,safflower oil rapeseed oil, tall oil, tallow oil, marine oils (e.g. fishoil, fish liver oil or whale oil), and synthetic and semisynthetic oilswhich are esters of aliphatic acids (e.g. Cardura E). Of these, linseedoil, soya bean oil and rapeseed are generally most preferred, especiallythe former. The choice of oil will depend, inter alia, upon the intendedend use of the ink, for example non-drying oils may be used in reactionproducts for use in cold set inks and soya bean oil is useful forreaction products for use in heat set inks. Oils are described, forexample, in "Printing Inks for Lithography", cited above, at pages45-58.

A wide variety of alkyd resins may be employed as starting materials forthe reaction product. The alkyd resin is preferably a long oil resin,preferably being derived from at least 50% by weight, more preferably60% to 90% by weight, of long chain carboxylic acids, especially fattyacids. Suitable fatty acids include saturated and unsaturated C₈ -C₂₂carboxylic acids such as oleic, ricinoleic, linolenic, linoleic,eleostearic, caprylic, capric, lauric, myristic, palmitic andpalmitoleic acids; typically employed in the form of mixtures of fattyacids derived from natural or synthetic oils such as those discussedabove. The fatty acid mixtures may be used in the form of theirnaturally occurring triglycerides. In addition to the fatty acid, thealkyd will also be derived from other usual components, namely one ormore polyhydric alcohols, such as glycerol, pentaerythritol, trimethylolpropane (TMP), trimethylolethane (TME), neopentyl glycol, ethyleneglycol, diethylene glycol, di-trimethylolpropane (di-TMP),dipentaerythritol; propylene glycol and 1,3-butane-diol; and one or morepolycarboxylic acids such as orthophthalic acid, isophthalic acid,terephthalic acid, trimellitic acid, pyromellitic acid, adipic acid,maleic acid, fumaric acid, benzoic acid, p-tertiary butyl benzoic acid,and abietic acid. Other types of alkyd include polyester modifiedacrylic and alkyd modified acrylic resins. The acidity of this alkydresin is not of particular importance and thus the alkyd resin maysuitably have an acid value from 0 to 100 mgKOH/g.

The reaction product is produced by reacting (cooking) the hard resinwith the oil and/or alkyd at elevated temperature, generally above 200°C. but more preferably in the range 220-260° C., for sufficient time toeffect reaction. Generally the time required will vary inversely withthe temperature and thus, for example, reaction may be carried out for aperiod of 6 hours at 220° C. down to a period of only 1 hour at 250° C.The reactions occurring during cooking are complex, leading to amultiplicity of reaction products, but probably involvetransesterification reactions which are well familiar to the printingink chemist (see, e.g. "Printing Inks for Lithography" at page 84). Theprogress of the reaction may be monitored by observation of variousparameters such as viscosity and tack (both of which vary withincreasing degree of reaction) and heptane tolerance (which increaseswith increasing degree of reaction). A principal characteristic of thereaction product used in accordance with the invention is that it has arelative high acid value, e.g. 40 to 200 mgKOH/g, especially 40 to 70mgKOH/g. It is noteworthy that when reacting a high acid value hardresin with a low acid value oil and/or alkyd resin (as in accordancewith the present invention) a product having a relatively high acidvalue is obtained, that is acidity of the starting material is retained.

The weight ratio of the high acid value hard resin to oil and/or alkydresin is suitably from 4:1 to 0.5:1, preferably 2:1 to 1:1, especially1.5:1 to 1:1.

The reaction is most preferably carried out under an inert atmosphere,e.g. nitrogen, to inhibit potential oxidation of any oxidisable species,especially drying species in the oil and/or alkyd and/or hard resin.

In accordance with a further embodiment, the present inventionencompasses a method for the production of a lithographic ink whichincludes the steps of reacting an acid functional hard resin (especiallyone having acid values as discussed above) with a fatty ester oil and/oralkyd resin at elevated temperature (preferably above 200° C.,especially from 220° C. to 250° C.) for a time sufficient to causereaction between the hard resin and the oil and/or alkyd (e.g 1 to 6hours) whereby to provide an acid functional reaction product preferablyhaving an acid value of from 40 to 200 mgKOH/g; and subsequentlycombining the said reaction product with a solution/diluent and acolorant to provide a lithographic printing ink.

It should be noted that the acid functional reaction products used inthe inks of the invention, whilst being capable of affordingalkali-washability to the inks, have unexpectedly been found to be goodbinders for use in lithographic printing inks. Accordingly, theinvention is intended to encompass not only alkali washable inks butinks intended for washing with conventional organic solvent systems andcontaining the acid functional reaction product as a binder.

A second essential component of the inks of the invention is asolvent/diluent and it has been found that the acid functional reactionproducts noted above are well compatible with a wide variety ofsolvent/diluents including fatty acid esters as well as petroleumdistillates and mineral oils. Examples of such fatty acid esters includethe methyl, ethyl, butyl and 2-ethylhexyl esters of tall oil fattyacids, coconut fatty acids, linseed oil fatty acids, soya oil fattyacids, palm oil fatty acids and rapeseed oil fatty acids; diethyleneglycol esters of tall oil fatty acid; methyl esters of lauric acid,myristic acid, palmitic acid and caprylic acid; methyl, butyl,2-ethylhexyl and isobutyl esters of oleic acid; oleic acid esters ofdiethylene and triethylene glycol; and dibutyl and di-2-ethylhexyladipates and sebacates. Accordingly, it is possible to formulate an inkin accordance with the invention entirely without mineral oil orpetroleum distillate diluent and this may be an advantage whenenvironmental and/or legal considerations place constraints on the useof mineral oils and/or petroleum distillates. It should, however, benoted that the reaction products are compatible with mineral oils andpetroleum distillates so that these may be used as all or a part of thesolvent/diluent system, if desired.

Commonly, in the production of an ink in accordance with the invention,at least a part of the solvent/diluent will be introduced by lettingdown (diluting) the reaction product after it has sufficiently cooled.

Together, the acid functional reaction product and solvent/diluent formthe essential ingredients of the varnish component of an ink inaccordance with the invention. Other resinous components may, and oftenwill, be present in the varnish component to serve, for example, toadjust the overall rheology of the ink, its pigment wetting ability,hardness, flexibility, setting speed, gloss, tack, adhesion, etc.Typical such other resins include alkyd resins and, in order to achievewater-washability characteristics for the final ink, when desired, theseadditional alkyd resins desirably have an acid value of from 0 to 100mgKOH/g, preferably 30 to 70 mgKOH/g. Furthermore, other hard resins maybe present in the varnish and these need not have high acid values. Suchother resins, such as alkyds or hard resins, may be introduced bydirectly compounding with the reaction product and solvent diluent orthey may be formulated themselves as a varnish, i.e. in combination withsolvent/diluent, and then that varnish blended with the varnishcomprising acid functional reaction product and solvent/diluent. Suchother varnish to be blended with the principal, acid functional reactionproduct-containing varnish may be produced as desired, for example by aso-called "cold cut" process or by hot dispersion dissolution attemperatures between 150 and 210° C. (see, e.g. "Printing Inks forLithography" at page 84). Where the additional resin is a low acid valuehard resin this may be introduced by incorporating it as an ingredientin the varnish before or after reaction. Where the final varnish is tobe water-washable, it has been found that it should have an overall acidvalue of 30- 80 mgKOH/g, preferably 40-70 mgKOH/g.

The varnishes of the inks of the present invention suitably contain from20 to 100% by weight, preferably 40 to 50% by weight, of acidic reactionproduct; from 0 to 25% by weight, preferably from 10 to 25% by weight,of other resinous binder components; and from 10 to 60% by weight,preferably from 10 to 30% by weight of solvent/diluent.

The third essential component of the inks of the invention comprises acolourant, which generally takes the form of a pigment. A wide varietyof pigments are suitable for use in the printing inks of the inventionand are discussed, for example, in "The Printing Ink Manual" FourthEdition, Leach ed., Van Nostrand Rheinhold, at pages 110-171. Suitably,the weight ratio of varnish to pigment in an ink in accordance with theinvention will be from 20:1 to 0.5:1, preferably 5:1 to 1:1. The varnishand pigment may be compounded by any desired appropriate manner, forexample on a three-roll mill or bead mill; e.g. as described in "ThePrinting Ink Manual" cited above at pages 624-644.

In addition to the above components, inks in accordance with theinvention may contain other ingredients, in particular drying agentswhen one or more components of the ink comprises or is derived from adrying or semi-drying oil. Suitable driers include primary driers suchas organic salts (e.g. octoates, tallates and napthenates) of transitionmetals such as cobalt and manganese. These primary driers may be used incombination with one or more auxilliary driers such as organic salts ofzinc and calcium. The use of drying agents in printing inks comprisingor derived from drying oils is well established and is discussed, forexample, in "The Printing Ink Manual", 2nd Edition, cited above, atpages 258-260.

Inks in accordance with the invention are intended for use in anylithographic printing process, including so-called "waterless" offsetlithography. As noted above, the inks of the invention may be designedto be washable with dilute alkaline solutions, e.g. 0.05 to 0.2 molarsolutions of alkalis such as sodium hydroxide or sodium carbonate. Inaddition to being potentially washable with aqueous media, the inks ofthe invention have various other advantageous properties. Thus, as notedabove, they may be formulated without using mineral oils or petroleumdistillates as solvent/diluent and, indeed, may be flexibly formulatedfor a wide range of printing applications and post-printingcharacteristics. Further, the final setting of an ink, after applicationto a substrate, is markedly assisted by the fact that any dryingcomponents, derived directly or indirectly from a drying vegetable oil,are chemically linked to the hard resin component. Furthermore, it hasbeen found that inks in accordance with the invention may not requirethe presence, in the fountain solution, of an alcohol such as isopropylalcohol.

In order that the invention may be well understood the followingExamples are given by way of illustration only.

In the Examples viscosity was measured on a Laray viscometer at 23° C.at 50% R.H. Tack was evaluated by testing a 0.3 ml sample at 100 rpm ona Prufbau Inkomat at 23° C. and 50% R.H. Heptane tolerance refers to theminimum volume (ml) of n-heptane which when added to 10 g of varnish and10 g of o-xylene causes precipitation at 23° C.

EXAMPLE 1 Preparation of Varnish I

A reaction product of an acid functional hard resin and a fatty esteroil.

27 Kg of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)were charged into a reactor which was then flushed with nitrogen tomaintain a nitrogen atmosphere therein. The linseed oil was heated to atemperature of 180-190° C. and 10 kg of a phenolic modified rosin esterhard resin having an acid value of <20 mgKOH/g (Albertol KP 351 exHoechst) were introduced into the reactor and the whole mixture stirreduntil the hard resin had become dispersed in the linseed oil (>20minutes). The temperature of the dispersion was then raised to 200° C.and 34 kg of a maleic modified rosin ester hard resin having an acidvalue of 190-205 mgKOH/g (K 1614 ex Lawter) were added to the dispersionwhich was then heated to a temperature between 240 and 245° C. andmaintained at that temperature for 1 hour and 30 minutes and then cooledto 190° C., after which 25 kg of coconut fatty acid methyl ester(Estisol 312 ex Esti Chem A/S) were added and the whole stirred for 10minutes. A further 4 kg of the coconut fatty acid methyl ester (Estisol312) were then added to the mixture which was then sampled for qualitycontrol tests and had a viscosity of 300 poise, a tack of 290, a heptanetolerance of 32 ml, and an acid value of 61 mgKOH/g (theoretical acidvalue 70 mgKOH/g). The resulting material was then filtered through a 50micron filter to give Varnish I.

EXAMPLE 2 Preparation of Varnish II

A modification of Varnish I with alkyd to give a wetting varnish.

85 Kg of Varnish I and 5 kg of an alkyd resin having an acid value ofabout 40 mgKOH/g (Hydrokyd 9 ex Lawter) were charged to a reactor andwere dispersed with heating to a temperature of 160° C. 6 Kg of a rosinmodified phenolic resin having an acid value of 15-20 mgKOH/g (KrumbhaarK42404 ex Lawter) were added to the dispersion which was homogenised for20 minutes. Then 4 kg of coconut fatty acid methyl ester (Estisol 312)were added to the homogenised mixture and the whole was then filteredthrough a 50 micron filter to give Varnish II, having a viscosity of 250poise, a tack of 325, a heptane tolerance of 33 ml, and an acid value of52 mg KOH/g (theoretical 55 mg KOH/g).

EXAMPLE 3 Preparation of Varnish III

A wetting varnish.

67 Kg of an alkyd resin having an acid value of about 40 mgKOH/g(Hydrokyd 9 ex Lawter) were added to a reactor and heated to 160° C.when 80 kg of a rosin modified maleic resin having an acid value of275-300 mgKOH/g (Alsynol RC 14 ex DSM) were added to the heated mixtureand the whole homogenised for 20 minutes after which 15 kg of coconutfatty acid methyl ester (Estisol 312) were added to the homogenisedmixture which was then filtered through a 50 micron filter to giveVarnish III having a viscosity of 165 poise, a tack of 385, a heptanetolerance of <100 ml, and an acid value of 80 mKOH/g (theoretical value82 mgKOH/g).

EXAMPLE 4 Preparation of Anti-setoff Paste

15 Kg of amorphous silica (WR Grace - Syloid 162C ex W. R. Grace) wereadded, in three lots, to 40 Kg of Varnish I, with mixing, and theresultant paste further diluted with a further 45 kg of Varnish I.

EXAMPLE 5 Preparation of Yellow Ink

A mixture of 4 kg of a first yellow pigment (arylamide Yellow 156), asecond yellow pigment (Jaune Diaryl GRE 2101) and 0.3 kg of ahydroquinone-containing antioxidant paste (HP 5025 ex SPCI) were mixedwith into a mixture of 36 kg of Varnish II and 7 kg of Varnish III, andthen ground on a three-roll mill. There were added to the resultantdispersion 17 kg of Varnish I, 12 kg of Varnish II, 3 kg of anti-setoffpaste, 5 kg of a micronised wax dispersant (Poliwax 33), 1 kg of anothermicronised wax dispersion (PC 843), 1 kg of a litho additive (Optilith4 - ex Lawter), 0.5 kg of another colourant (Iberian Orange concentrate)and the whole was then homogenised. 1 kg of mixed driers and 2.5 kg of amanganese drier (Soligen Manganese 6% LS 5X) were added to thehomogenised mixture which was further mixed and finally 1.7 kg ofcoconut oil fatty acid methyl ester (Estisol 312) added thereto, to givea yellow ink having a viscosity of 365 poise and tack of 155.

EXAMPLE 6 Production of Black Ink

8 Kg of a blue pigment (Alkali Blue SR 1118), 4 kg of a black pigment(Printex Black 35), 14 kg of a black pigment (Printex Black 45) and 0.3kg of antioxidant paste (HP 5025) were dispersed into a mixture of 33 kgof Varnish II and 13.5 kg of Varnish III in a three-roll mill. A mixtureof 13.7 kg of Varnish I, 2.5 kg of anti-setoff paste, 4.4 kg ofmicronised wax (Poliwax 33), 1 kg of micronised wax (PC 843) and 1 kg oflitho additive (Optilith 4) were mixed into the resulting dispersionfollowed by 1 kg of mixed driers and 3 kg of manganese drier (SoligenManaganese 6% LS5X). Finally 1 kg of coconut oil fatty acid methyl ester(Estisol 312) was incorporated in the mixture to give the black inkhaving a viscosity of 360 poise and a tack of 160.

EXAMPLE 7 Production of Cyan Ink

16 Kg of Cyan pigment (Cyanine Lutetia J500) and 0.3 kg of antioxidantpaste (HP 5025) were dispersed, on a three roll mill, into a mixture of37 kg of Varnish II and 12 kg of Varnish III. There were then mixed intothe dispersion 19 kg of Varnish I, 3 kg of anti-setoff paste, 4 kg ofmicronised wax (Poliwax 33), 1 kg of micronised wax (PC 843) and 1 kg oflitho additive (Optilith 4). There were then added 1 kg of mixed driersand 2.5 kg of the manganese drier (Soligen Manganese 6% LS5X) followedby 3.2 kg of coconut fatty acid methyl ester (Estisol 312) to give theCyan ink, having a viscosity of 350 poise and a tack of 180.

EXAMPLE 8 Production of Magenta Ink

18 Kg of pigment (Rubis Lithol D 4568 DD) and 0.3 kg of antioxidantpaste were dispersed, on a three roll mill, into a mixture of 34 kg ofVarnish II and 15 kg of Varnish III. There were mixed into thedispersion 18.2 kg of Varnish I, 3 kg of anti-setoff paste, 5 kg ofmicronised wax (Poliwax 33), 1 kg of micronised wax (PC 843) and 1 kg oflitho additive (Optilith 4). There were then introduced into the mixtureI kg of mixed driers and 2.5 kg of manganese drier (Soligen Manganese 6%LS5X), followed by 2 kg of coconut fatty acid methyl ester (Estisol 312)to give a magenta ink having a viscosity of 350 poise and a tack of 155.

EXAMPLE 9

The inks of examples 5 to 8 were printed on Maine Club 115 gm stockusing a 4 colour Heidelberg MO press fitted with OCS 72 blankets and anAlcolor damping unit. The fountain solution was Vegra Blue 3300 whichcontained 10% isopropyl alcohol and had a pH of 5.0. The press was runat speeds of up to 8000 impressions an hour, and at least 3000 sheetswere printed. Offset behaviour on the press, lithographic performance,setting time and print quality were all good. After printing, therollers and blankets were readily cleaned using a water-based wash-upsolution (B-546 from Deluxe) of pH 10. The plates were readily cleanedusing a water-based wash-up solution (8-590 from Deluxe).

EXAMPLE 10

A similar test to that described in Example 9 was conducted, except thatthe fount solution was water containing 3% Hydralcool (ex CSFI), i.e.alcohol free, and had a pH of 4.53. Offset behaviour on the press,lithographic performance, setting time and print quality were all good.After printing, the rollers and blankets were readily cleaned using awater-based wash-up solution (B-546 from Deluxe) of pH 10.

Varnishes IV to VI show a range of formulating options. An acidfunctional hard resin can be reacted solely with an alkyd (Varnish IV),with an alkyd and a fatty ester oil (Varnish V), or solely with a fattyester oil (Varnish VI) to give alkali-soluble or dispersible binderswhich form the basis for water washable lithographic inks.

EXAMPLE 11 Varnish IV

A reaction product of an acid functional hard resin and an alkyd.

20g of a long oil linseed alkyd having an acid value of 12mg KOH/gmaximum (Surkyd 119 ex Mitchanol) and 10 g of a tall oil fatty acidester having an acid value of 2 mg KOH/g (Nirez 9012 ex Arizona) werecharged to a reactor. The reactor was then flushed with nitrogen tomaintain a nitrogen atmosphere therein, and the reaction mixture heatedto 160-170° C. There were then added 32 g of a rosin modified fumarichard resin having an acid value of 210 mg KOH/g (Filtrez 575 ex AkzoNobel), and 8 g of a hard resin having an acid value of <20 mg KOH/g (XR1769 ex Lawter). The reaction mixture was heated to 230° C. andmaintained at this temperature for 30 minutes. A further 30 g of Nirez9012 were added for purposes of viscosity adjustment to give a clearvarnish with the following characteristics:

Viscosity - 370 poise

Tack - 424-410

Acid value - 64.5 mg KOH/g (theoretical acid value 69.8 mg KOH/g).

The resulting mixture was filtered through a 50 micron filter to giveVarnish IV.

EXAMPLE 12 Varnish V

A reaction product of an acid functional hard resin, a fatty ester oiland an alkyd.

450 g of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)and 150 g of a long oil linseed alkyd (Printorob I 84ST ex Robbe) werecharged to a reactor which was then flushed with nitrogen to maintain anitrogen atmosphere therein. The linseed oil was heated to a temperatureof 180 to 200° C. before adding 600 g of a maleic modified rosin esterhard resin having an acid value of 190-205 mg KOH/g (Krumbhaar K1614 exLawter). The reactants were heated at 230° C. for one hour, and then at240° C. for a further 2 hours and 30 minutes. After cooling to 180° C.300 g of coconut fatty acid methyl ester (Estisol 312 ex Esti Chem A/S)were stirred in. Samples taken after 24 hours showed the followingcharacteristics:

Viscosity - 480 poise

Tack - 310

Heptane tolerance - 70ml

Acid value of 62 mg KOH/g (theoretical acid value 78 mg KOH/g).

The resulting mixture was filtered through a 50 micron filter to giveVarnish V.

EXAMPLE 13 Varnish VI

A reaction product of an acid functional hard resin and a fatty esteroil.

40 g of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)were charged into a reactor which was then flushed with nitrogen tomaintain a nitrogen atmosphere therein. The linseed oil was heated to atemperature of 180-200° C. before adding 40 g of a maleic modified rosinester hard resin having an acid value of 190-205 mg KOH/g (KrumbhaarK1614 ex Lawter). The reaction mixture was then heated to 250° C. andmaintained at this temperature for 1 hr 30 min before cooling to 110° C.and adding 10 g of tall oil fatty acid ester having an acid value of 2mg KOH/g (Nirez 9012 ex Arizona) and 1.8 g of an gelling agent inmineral oil (40% by weight of Additol VXL 12 ex Hoechst in Scriptane 280ex Haltermann). The mixture was re-heated to 180° C., maintained at thistemperature for 10 minutes, and then a further 7.0 g of Nirez 9012 addedto give a clear varnish with the following characteristics:

Viscosity - 240 poise

Tack- 265

Heptane tolerance - 50 ml

Acid value of 68 mg KOH/g (theoretical acid value 78 mg KOH/g).

The resulting mixture was filtered through a 50 micron filter to giveVarnish VI.

Varnishes VII and VIII illustrate the use of acid functional hard resinswith differing acid values.

EXAMPLE 14 Varnish VII

A reaction product of an acid functional hard resin and a fatty esteroil, with one hard resin having an acid value of 53 mg KOH/g, and asecond hard resin having an acid value of 157 mg KOH/g.

27 g of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)were charged into a reactor which was then flushed with nitrogen tomaintain a nitrogen atmosphere therein. The linseed oil was heated to atemperature of 190° C. before adding 25 g of a rosin modified phenolichard resin having an acid value of 53 mg KOH/g (Krumbhaar K4664 exLawter) and 20 g of a modified rosin hard resin having an acid value of157 kg KOH/g (Grafofen 3412 ex Cremona). The mixture was then heated at240° C. for 45 minutes and 25 g of coconut fatty acid methyl ester(Estisol 312 ex Esti Chem A/S) stirred in. Samples were taken and showedthe following characteristics:

Viscosity - 210 poise

Tack- 300

Heptane tolerance - 50 ml

Acid value - 47 mg KOH/g (theoretical acid value 47 mg KOH/g).

The resulting mixture was filtered through a 50 micron filter to giveVarnish VII.

EXAMPLE 15 Varnish VIII

A reaction product of an acid functional hard resin and an alkyd, withthe hard resin having an acid value of 286 mg KOH/g.

20 g of a long oil linseed alkyd having an acid value of 12 mg KOH/gmaximum (Surkyd 119 ex Mitchanol) and 10 g of a tall oil fatty acidester having an acid value of 2 mg KOH/g (Nirez 9012 ex Arizona) werecharged to a reactor. The reactor was then flushed with nitrogen tomaintain a nitrogen atmosphere therein, and the reaction mixture heatedto 160-170° C. There were then added 20 g of a rosin modified maleicresin having an acid value of 275-300 mg KOH/g (Alsynol RC 14 ex DSM),and 22 g of a rosin modified phenolic resin having an acid value of <10mg KOH/g (Alsynol RL58 ex DSM). The reaction mixture was heated to 230°C. and maintained at this temperature for 30 minutes, when samples weretaken showing the following characteristics:

Viscosity - 360 poise

Tack- 425-410

Acid value - 61.7 mg KOH/g (theoretical acid value 60 mg KOH/g).

A final viscosity adjustment was made by stirring in 29 g of a tall oilfatty acid ester having an acid value of 2 mg KOH/g (Nirez 9012 exArizona). The resulting mixture was filtered through a 50 micron filterto give Varnish VIII.

Varnishes IX and X show how it is possible to formulate with a widerange of compositions. Varnish IX has a ratio of hard resin to oil of4:1, while Varnish XI has a ratio of hard resin to oil of 0.65:1.

EXAMPLE 16 Varnish IX

Ratio of hard resin to oil of 4:1.

250 g of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)were charged into a reactor which was then flushed with nitrogen tomaintain a nitrogen atmosphere therein. The linseed oil was heated to atemperature of 180-200° C. before adding 750 g of a rosin modifiedphenolic hard resin having an acid value of 135 mg KOH/g (Jonrez RP 305ex Westvaco Chemicals) and 250 g of a maleic modifed rosin ester hardresin having an acid value of 190-205 mg KOH/g (Krumbhaar K1614). Themixture was then heated with stirring at 230° C. for 2 hours 15 minuteswhen a heptane tolerance of 63 ml was reached. A final viscosityadjustment was made by stirring in 425 g of coconut fatty acid methylester (Estisol 312 ex Esti Chem A/S). Samples take after 24 hours showedthe following characteristics:

Viscosity - 421 poise

Tack - 500-480

Heptane tolerance - 63 ml

Acid value - 95 mg KOH/g (theoretical acid value 90 mg KOH/g).

The resulting mixture was filtered through a 50 micron filter to giveVarnish IX.

EXAMPLE 17 Varnish X

Ratio of hard resin to oil of 0.65:1.

600 g of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)were charged into a reactor which was then flushed with nitrogen tomaintain a nitrogen atmosphere therein. The linseed oil was heated to atemperature of 180-200° C. before adding 150 g of a fumaric resin havingan acid value of 250 mg KOH/g (Valke AF12 ex Forchem OY) and 150 g of amaleic resin having an acid value of 25 mg KOH/g (TPValkeres 5715 exForchem OY. The mixture was then heated at 230° C. for one hour,whereupon a further 90 g of TPValkeres 5715 were added to adjustviscosity. After a further one hour, samples were taken which showed thefollowing characteristics:

Viscosity - 54 poise

Tack - 187

Heptane tolerance - 80 ml

Acid value - 39 mg KOH/g (theoretical acid value 44 mg KOH/g).

The resulting mixture was filtered through a 50 micron filter to giveVarnish X.

EXAMPLE 18 Varnish XI

Includes petroleum distillate.

160 g of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)and 150 g of a long oil linseed alkyd (Printorob I 84ST ex Robbe) werecharged into a reactor which was then flushed with nitrogen to maintaina nitrogen atmosphere therein. These were heated to a temperature of 180to 200° C. before adding 300 g of a maleic modified rosin ester hardresin having an acid value of 190-205 mg KOH/g (Krumbhaar K1614 exLawter) and 450 g of a rosin modified phenolic resin having an acidvalue of 135 mg KOH/g. The reactants were heated at 230° C. for threehours, when samples showed the following characteristics:

Viscosity - 424 poise

Tack- 503

Heptane tolerance - 56 ml

Acid value - 78 mg KOH/g (theoretical acid value 81 mg KOH/g).

Then 420 g of a petroleum distillate (Scriptane 260 ex Haltermann) wereadded. The resulting mixture was filtered through a 50 micron filter togive Varnish XL.

EXAMPLE 19 Varnish XII

Suitable for use in waterless litho.

600 g of heat treated linseed oil (Huile de Lin Stabilisee ROB ex Robbe)were charged into a reactor which was then flushed with nitrogen tomaintain a nitrogen atmosphere therein. The linseed oil was heated to atemperature of 180-200° C. before adding 600 g of a maleic modifiedrosin ester hard resin having an acid value of 190-205 mg KOH/g(Krumbhaar K1614 ex Lawter). The reaction mixture was then heated to250° C. and maintained at this temperature for 2 hours before adding 180g of coconut fatty acid methyl ester (Estisol 312 ex Esti Chem A/S). Oncooling to 110° C., 27 g of a gelling agent in mineral oil (40% byweight of Additol VXL 12 ex Hoechst in Scriptane 280 ex Haltermann) wereadded, and the mixture re-heated to 180° C. and maintained at thistemperature for 10 minutes. A further 30 g of Estisol 312 were added toadjust the viscosity. Samples were taken and showed the followingcharacteristics:

Viscosity - 539 poise

Tack - 262

Heptane tolerance - 56 ml

Acid value - 73 mg KOH/g (theoretical acid value 81 mg KOH/g).

The resulting mixture was filtered through a 50 micron filter to giveVarnish XII.

In the inks of Examples 20-27, all formulations are shown as 100 partformulations by weight. Where the figures in any example total more orless than 100, they should be factored proportionately to 100.

EXAMPLE 20 Yellow ink based on Varnishes IV and VI

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish IV            54.8                                                      Yellow pigment 13.0                                                           Alkyd resin (Hydrokyd 9 ex Lawter) 2.0                                        Antioxidant paste (HP5025 ex SPCI) 0.5                                      ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VI            15.0                                                      Orange colourant 0.5                                                          Polyethylene wax 7.0                                                          Anti-set-off paste 4.0                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 1.2                                                                     Tall oil fatty acid ester 3.0                                                 (Nirez 9012 ex Arizona)                                                     ______________________________________                                    

This yellow ink had a viscosity of 310 poise and tack of 200. [Itsvarnish to pigment ratio is 5.4:1, and the ratio of acid functional hardresin to oil/alkyd is 1.24:1]

EXAMPLE 21 Black ink based on Varnishes IV and VI

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish IV            40.3                                                      Printex 45 (ex Degussa) 18.0                                                  Alkyd (Hydrokyd 9 ex Lawter) 5.0                                              Antioxidant paste (HP5025 ex SPCI) 0.7                                      ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VI            12.0                                                      Bleu Alcali 61SR1118 6.0                                                      Polyethylene wax 6.0                                                          Anti-set-off paste 4.0                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 3.0                                                                     Tall oil fatty acid ester 6.0                                                 (Nirez 9012 ex Arizona)                                                     ______________________________________                                    

This black ink had a viscosity of 315 poise and tack of 154.

EXAMPLE 22 Cyan ink based on Varnishes IV and VI

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish IV            51.0                                                      Phthalocyanine blue pigment 16.0                                              Alkyd (Hydrokyd 9 ex Lawter) 4.0                                              Antioxidant paste (HP5025 ex SPCI) 0.5                                      ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VI            12.3                                                      Polyethylene wax 6.0                                                          Anti-set-off paste 4.0                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 1.2                                                                     Tall oil fatty acid ester 4.0                                                 (Nirez 9012 ex Arizona)                                                     ______________________________________                                    

This cyan ink had a viscosity of 350 poise and tack of 185.

EXAMPLE 23 Magenta ink based on Varnishes IV and VI

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish IV            48.0                                                      Red pigment 18.0                                                              Alkyd (Hydrokyd 9 ex Lawter) 5.0                                              Antioxidant paste (HP5025 ex SPCI) 0.5                                      ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VI            12.3                                                      Polyethylene wax 6.0                                                          Anti-set-off paste 4.0                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 1.2                                                                     Tall oil fatty acid ester 4.0                                                 (Nirez 9012 ex Arizona)                                                     ______________________________________                                    

This magenta ink had a viscosity of 410 poise and tack of 180.

EXAMPLE 24 Yellow ink based on Varnishes III and VII

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish III           11.0                                                      Yellow pigment 13.0                                                           Alkyd (Hydrokyd 9 ex Lawter) 3.2                                              Antioxidant paste (HP5025 ex SPCI) 0.5                                        Varnish VII 28.0                                                            ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VII              31.8                                                   Orange colourant 0.5                                                          Polyethylene wax 5.0                                                          Anti-set-off paste 3.0                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 1.5                                                                     Estisol 312 ex Esti Chem A/S to adjust viscosity.                           ______________________________________                                    

This yellow ink had a viscosity of 250 poise and tack of 213. [It has aratio of acid functional hard resin to oil/alkyd of 1.57:1]

EXAMPLE 25 Black ink based on Varnishes III and VII

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish III           12.0                                                      Carbon black (Printex 45 ex Degussa) 18.0                                     Alkyd (Hydrokyd ex Lawter) 6.6                                                Antioxidant paste (HP5025 ex SPCI) 0.5                                        Varnish VII 28.0                                                              Alkali Blue 8.0                                                             ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VII              15.6                                                   Polyethylene wax 5.0                                                          Anti-set-off paste 2.5                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 1.8                                                                     Estisol 312 ex Esti Chem A/S to adjust viscosity.                           ______________________________________                                    

This black ink had a viscosity of 280 poise and tack of 177.

EXAMPLE 26 Cyan ink based on Varnishes III and VII

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish III           12.0                                                      Phthalocyanine blue pigment 16.0                                              Alkyd (Hydrokyd 9 ex Lawter) 6.1                                              Antioxidant paste (HP5025 ex SPCI) 0.5                                        Varnish VII 31.5                                                            ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VII              20.9                                                   Polyethylene wax 5.0                                                          Anti-set-off paste 3.0                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 1.5                                                                     Estisol 312 ex Esti Chem A/S to adjust viscosity.                           ______________________________________                                    

This cyan ink had a viscosity of 215 poise and tack of 190.

EXAMPLE 27 Magenta ink based on Varnishes III and VII

A procedure similar to that of Example 5 was followed. The initialmixture consisted of:

    ______________________________________                                        Varnish III           13.0                                                      Red pigment 18.0                                                              Alkyd (Hydrokyd 9 ex Lawter) 7.3                                              Antioxidant paste (HP5025 ex SPCI) 0.4                                        Varnish VII 29.0                                                            ______________________________________                                    

These components were ground on a three-roll mill and then mixed with:

    ______________________________________                                        Varnish VII              20.3                                                   Polyethylene wax 5.0                                                          Anti-set-off paste 3.0                                                        Litho additive (Optilith 4 ex Lawter) 1.0                                     Drier 1.6                                                                     Estisol 312 ex Esti Chem A/S to adjust viscosity.                           ______________________________________                                    

This magenta ink had a viscosity of 215 poise and tack of 190.

EXAMPLE 28 Tests of ink performance and water washability

The inks of Examples 20-27 were tested for ink performance and waterwashability as in Examples 9 and 10. For all the inks, offset behaviouron the press, lithographic performance, setting time and print qualitywere good. All the inks were readily cleaned up from the rollers,blankets and plates using the water-based wash solutions of Examples 9and 10.

I claim:
 1. A lithographic printing ink comprising an alkali-soluble ordispersible binder material which is the reaction product of an acidfunctional hard resin with a fatty ester oil and/or an alkyd resin,wherein the acid functional hard resin has an acid value of at least 50mgKOH/g and a weight ratio of the acid functional hard resin to oil plusalkyd resin is from 4:1 to 0.5:1.
 2. The printing ink as claimed inclaim 1, in which the said reaction product has an acid value of from 40to 200 mgKOH/g.
 3. The printing ink as claimed in claim 1, which inkfurther comprises a solvent and/or diluent selected from the groupconsisting of a fatty ester oil, mineral oil and petroleum distillateand mixtures thereof.
 4. The printing ink as claimed in claim 1 alsocontaining one or more other resinous components.
 5. The printing ink asclaimed in claim 1, which ink comprises a varnish which contains from 20to 100% by weight of acid functional reaction product; from 0 to 25% byweight of other resinous binder component(s); and from 10 to 60% byweight of solvent/diluent.
 6. The printing ink as claimed in claim 5,comprising a pigment in an amount such that the weight of the varnish topigment is from 20:1 to 0.5:1.
 7. A method of printing onto a substrate,the method comprising a step of depositing by lithography, an inkaccording to claim 1, onto the substrate.